Thermal contact resistance

OK I'll try indium too. (a bit more spendy than silicone indium gasket, or solder, or weld. I thought, though, that best thermal

We did these tapered metal seals (ala Eric Smith, Cornell) for vacuum cans that were only sealed with vacuum grease.

George H.

this may be why some processor heatsink interface pads are what appear to be a thin sheet of lead. I've not seen this in PC hardware, but I have seen it in more serious unix servers.

The plus side is there's no mess when replacing a cpu or heatsink, and repair times in the field are very fast.

resistance,

to

When i had to deal with that kind of joining material it was a 3 mil sheet of indium. I could tell it from lead because it stayed shiny better.

?-)

Yes, apparently the contact area was square micrometers in the test I did. I was expecting the thermal conduction to be small, but I was not expecting it to be vanishing toward zero! I'm glad I did this test and saw the results with my own eyes, I would have had a hard time believeng somebody who told me about it.

Jon

Do you know of an easy indium test? I have some of these heatsinks with the now scuffed up metal interface pads. The material is very soft whatever it is.

You could try and measure the melting point. Indium is fairly low. (157 C according to wiki)

George H.

resistance,

to

sheet

It could be indium. I have seen it once, and used it that way. Rather expensive. It was for a space application. I also had a sheet of kovar as part of my (employer's) lab materials once.

?-)